Abstract

Terminal heat stress causes an array of physiological, biochemical and morphological changes in plants, which affect plant growth and development. In present investigation, real time quantitative expression analysis of HSP90 gene in root showed a maximum of 2.5 fold increase in the transcript level during seed hardening stage. Similarly, in flag leaf 4.5, 4.3 and 6.5 fold increases in the transcript level were observed during pollination, milky dough and seed hardening stages, respectively. A decrease in the cell membrane stability (from 70 to 65%) was observed with growth and development of wheat. An altered expression of H₂O₂ was observed with highest expression at milky dough stage (0.9 µg/g fresh weight). The highest accumulation of H₂O₂ was observed in response to heat shock of 42°C for 2 h. There was a remarkable decline in proline quantity at different stages of growth with lowest accumulation at seed hardening stage. Under differential heat shock, the highest activity of SOD and CAT were observed in response to heat shock of 40°and 35°C for 2 h. The results from this study suggest a potential role for antioxidant enzymes in the reduction of elevated levels of H₂O₂ in wheat plants grown under heat stress condition.

Key words: Antioxidant enzymes, wheat, heat stress, cell membrane stability, proline, hydrogen peroxide.